"Most of the houses with no power are in Vaasa – 1,203, Pori – 1,195, Kristinestad – 1,109," the spokesperson said late on Sunday, adding that a total of 67 towns and cities are experiencing power issues.
Meanwhile in France, about 60,000 of households are without electricity because of Storm Dennis, according to France Bleu radio.
According to the Normandy branch of the Enedis energy company, there was a peak in the number of homes with no power on Sunday afternoon.
"In the middle of the afternoon, Normandy saw a peak of 11,000 customers without electricity," a statement released on the Enedis en Normandie Twitter account says.
The United Kingdom saw a record number of flood warnings issued across the country amid the storm.